The Internet of Things (IoT) communication is a kind of network technology that is being actively developed at present. With this technology, different devices can be connected in a network to communicate with and exchange data with each other. Most of the IoT communication technologies utilize an unlicensed band, so the security and communication quality cannot be ensured. Accordingly, the Narrowband Internet of Things (NB-IoT) that adopts a licensed band is advantageous.
Also because of its wide communication range, low power consumption, low computation complexity and low hardware cost, NB-IoT has become the IoT technology that are the most actively developed at present. Unfortunately, the existing NB-IoT technology still has the problem of unnecessary power consumption.
Specifically, in the NB-IoT system, usually a user equipment transmits a random access preamble repeatedly in a designated Narrowband Physical Random Access Channel (NPRACH) during a preset NPRACH transmission period.
However, if the base station that detects the random access preamble during the NPRACH transmission period is to transmit a random access response to the user equipment, the random access response cannot be received by the user equipment until the end of the NPRACH transmission period.
As a consequence, the user equipment unnecessarily transmits the random access preamble repeatedly during the time interval from the time when the random access preamble is detected by the base station to the end of the NPRACH transmission period to cause unnecessary power consumption. Accordingly, efforts have to be made in the art to overcome this problem.